The Effect Of Corosolic Acid On Glucose Metabolism In Insulin-Resistant Cells And Research Of Related Mechanism

Objective To investigate the effect of corosolic acid on glucose metabolism in insulin-resistant3T3-L1adipocytes and HepG2cells, and explore the potential mechanism.Methods Insulin resistance in3T3-L1adipocytes was induced with high glucose and hyperinsulinism. The cells were then treated with corosolic acid of different concentrations for twenty-four hours, and further assigned to three groups, normal control group, insulin-resistant model group and metformin positive control group. The glucose concentration in cell culture medium was detected though glucose oxidase method. RT-PCR was performed to evaluate mRNA expression of glucose transporter-4(GLUT-4), insulin receptor substrate-1(IRS-1) and Cb1related protein (CAP). In addition, the insulin-resistant HepG2cells were also induced to verify these effects.Results Both corosolic acid and metformin could increase the glucose metabolism of3T3-L1adipocytes and HepG2cells with insulin resistance:Firstly, in insulin-resistant3T3-L1adipocytes, which treated with0.001,0.005,0.01,0.1,0.5and1mmol/L corosolic acid, the glucose consumption increased by5.60%、12.56%、22.82%、48.79%27.80%、19.35%respectively. The peak value was observed at0.1mmol/L. In cells treated with0.001,0.01,0.1,0.5and1mmol/L metformin, glucose consumption increased by2.44%,10.78%,28.49%,56.02%and55.04%respectively, and the glucose consumption reached to the peak level at0.5mmol/L; Compared with metformin cases at the same concentration, in low concentration (0.001～0.1mmol/L) corosolic acid had a better effect, and the maximum glucose consumption of them was very close to the normal level, while the required concentration of corosolic acid was1/5of metformin. Compared with model group, the gene expression of GLUT-4and IRS-1in corosolic group increased by34.27%、22.05%respectively, and in metformin group increased by39.24%、28.57%respectively. Secondly, glucose consumption of HepG2cells treated with corosolic acid of different concentrations (0.001,0.01, 0.1,0.5and lmmol/L), increased by0.7%,8.7%,16.5%,16.2%and11.0%, respectively.Conclusion Corosolic acid could promote the glucose metabolism of adipocytes and HepG2cells with insulin resistance, and revert the insulin resistance; Its mechanism may relate to the elevated gene expression of GLUT-4and IRS-1.